MAY 2017 Sub. Code: 1604
M. OPTOM DEGREE EXAMS
FIRST YEAR
PAPER IV CONTACT LENS I
Q.P. Code: 281604
Time: Three hours Maximum: 100 Marks
I. Elaborate on: x 20 40)
1. Explain the steps involved before, during and after fitting a rigid contact lens to a
patient.
2. For the following case examples, tabulate Your lens of choice Why you
chose this lens, Calculate 1st trial lens base curve/diameter/power/ optic zone
diameter, considering a vertex distance of 12mm, dilated pupil size 6mm, corneal
diameter 11mm.
Case Ms. spectacle Rx OD: +4.50DS, K readings 46.00 90&46.50 180.
Case Mr. spectacle Rx OS: -3.00DS/-1.00DC x 180, K readings 45.00 90
44.00 180.
Case Mr. spectacle Rx OD: -4.00DS /-2.50DC x 90, K readings 47.00 180
44.00 90.
Case Ms. spectacle Rx OS: -3.00DS/-1.50DC x180, K readings 45.00
90 45.00 180.
II. Write notes on: (10 x 6 60)
1. Define "tear lens". Write about the role of tear film and tear lens in soft and rigid
contact lens fitting.
2. Explain why thickness is an important design feature in the selection of
soft CL RGP CL.
3. What is a contact lens care system? Write about the various ingredients and their
actions.
4. Write about RGP contact lens manufacturing techniques.
5. Explain about the effect of contact lens on corneal nutrition, metabolism and
hydration dynamics.
6. What are the characteristics of an ideal fitting RGP contact lens on spherical
cornea, and toric cornea? Explain with diagrams.
7. Name few RGP materials. Write about the advantages and disadvantages of RGP
CLs.
8. Explain the rigid contact lens insertion and removal techniques.
9. Silicone hydrogel contact lenses properties, advantages and disadvantages.
10.Define the parameters sagittal depth, total diameter and base curve. Explain the
relationship between them with diagrams.